The production of sterols from distillates obtained in the deacidification of vegetable oils or from distillation residues accumulating in the production of methyl esters and more particularly in the production of methyl esters from crops for “biodiesel” applications is generally known.
One known process for the production of sterols has been described wherein a residue from the distillation of methyl esters essentially consisting of glycerides, sterols, sterol esters and tocopherols is transesterified with methanol in the presence of alkaline catalysts. However, the sterol yield is unsatisfactory. Although some improvements have been made, including the utilization and revaluation of residues from the production of fats and oils and their constituents, such improvements can involve costly, elaborate processes using ecologically harmful solvents. For example, in some processes readily volatile sterols from the distillation residues of fat and oil production and working up are isolated by transesterification and subsequent dissolution in aprotic organic solvents.
Accordingly, the problem addressed by the present invention was to produce sterols in high yields and high purity by an economic process that would avoid toxicologically and ecologically unsafe solvents and, at the same time, to utilize residues from fatty acid production more economically.